Enhancement of the superconducting transition temperature in Nb/permalloy bilayers by controlling the domain state of the ferromagnet

In (S/F) hybrids the suppression of superconductivity by the exchange field h(ex) of the ferromagnet can be partially lifted when different directions of h(ex) are sampled simultaneously by the Cooper pair. In F/S/F trilayers where the magnetization directions of the F layers can be controlled separately, this leads to the so-called spin switch. Here we show that domain walls in a single F layer yield a similar effect. We study the transport properties of Ni(0.80)Fe(0.20)/Nb bilayers structured in strips of different sizes. For large samples a clear enhancement of superconductivity takes place in the resistive transition, in the very narrow field range (order of 0.5 mT) where the magnetization of the Py layer switches and many domains are present. This effect is absent in microstructured samples.     

To the structure identification of a nonlinear regulator for a nonstationary hyperbolic system

Necessary and sufficient conditions are found for the solvability of the inverse problem of realizing a nonstationary polylinear regulator for a hyperbolic system such that all processes in a given bundle (of any cardinality) of nonlinear infinite-dimensional controlled (by means of program and feedback controls) dynamic processes in a separable Hilbert space are its admissible solutions.     

The asymptotics of distribution functions in fluid-filled finite slits

Asymptotic formulas have been derived for distribution functions in cylindrical slits with finite cross-section radii. The problem has been solved based on the asymptotic principle of interbody interactions within the framework of dispersion forces. Symmetric and asymmetric slits between two identical cylinders and between a cylinder and a planar infinite solid surface have been considered. Calculations have been performed for a symmetric slit with a width equal to two cylinder radii.     

Morpholine-substituted soluble polyimides

The interaction of undescribed 1,3-diamino-4-morpholinebenzene with dianhydrides of various aromatic tetracarboxylic acids yields morpholine-substituted soluble polyimides. The thermal properties of these polymers are studied.     

Activity coefficients in an ionic micellar system

The average activity coefficients of ionic surfactants as a whole and their monomeric forms are compared. The concept of an aggregative activity coefficient is introduced.     

Reaction of 1-tosyl-2,2-dichloroenamines with the Lawesson’s reagent

In the reaction of the available 1-tosyl-2,2-dihlorenamides with the Lawesson??s reagent the derivatives of 4-tosyl-1,3-thiazole were shown to form containing a labile chlorine atom at the C⁵ position. This fact was used for the synthesis of a number of the previously unknown bifunctionally substituted 4,5-thiazoles.     

Interaction of 2-aryl-4-cyano-1,3-oxazole-5-sulfonyl chlorides with amidines

Reaction of 4-cyano-1,3-oxazole-5-sulfonyl chlorides with amidines results in new 7-amino-1,3-oxazolo[5,4-d]pyrimidines. Their structure was confirmed by spectral methods and X-ray diffraction analysis.     

The First Examples of Donor-Stabilized Phosphanetriyl-Phosphonium [RP2]+ Ions

Abstract

Synthesis of the first donor-stabilized phosphanetriylphosphonium ion [Ar?PP<-PPh₃]⁺ via trifluoromethanesulfonic acid (TfOH) induced reaction of P-dialkylaminodiphosphenes, Ar?P=PNR₂ (Ar? = 2,4,6-tri-tert-butylphenyl) with triphenylphosphane has been described.     

Synthesis of 7-iodo(arylsulfanyl)methyl-7,8-dihydro-[1,3]thiazolo[2,3-i]purinium pentaiodide (perchlorates) and their transformation into 4-amino-5-(1,3-thiazol-2-yl)imidazole derivatives

Intramolecular electrophilic cyclization of 6-allylsulfanylpurine by the action of iodine and arenesulfenyl chlorides gave 7-iodomethyl-7,8-dihydro[1,3]thiazolo[2,3-i]purin-6-ium pentaiodide and 7-arylsulfanylmethyl-7,8-dihydro[1,3]thiazolo[2,3-i]purin-6-ium perchlorates, respectively. 7-Iodomethyl-7,8-dihydro-[1,3]thiazolo[2,3-i]purin-6-ium iodide reacted with sodium and potassium alkoxides to produce alkyl N-[5-(4-methyl-1,3-thiazol-2-yl)-1H-imidazol-4-yl]formimidates, and its reaction with secondary cyclic amines afforded 5-(4-methyl-1,3-thiazol-2-yl)-N-[morpholin-4-yl(or piperidin-1-yl)methylidene]-1H-imidazol-4-amines. Successive treatment of 7-arylsulfanylmethyl-7,8-dihydro[1,3]thiazolo[2,3-i]purin-6-ium perchlorates with sodium acetate and morpholine led to the formation of 5-(4-arylsulfanylmethyl-4,5-dihydro-1,3-thiazol-2-yl)-N-(morpholin-4-ylmethylidene)-1H-imidazol-4-amines.